A retired United States Army lieutenant colonel and Fox News contributor quit Tuesday and denounced the network and President Donald Trump in an email to colleagues.

"Fox has degenerated from providing a legitimate and much-needed outlet for conservative voices to a mere propaganda machine for a destructive and ethically ruinous administration," wrote Ralph Peters, a Fox News "strategic analyst."

"Over my decade with Fox, I long was proud of the association. Now I am ashamed," he wrote.

Peters, who was also a heated critic of Barack Obama's foreign policy, once described him as having been "date raped" by Vladimir Putin. He didn't respond to an email about his missive.

“Ralph Peters is entitled to his opinion despite the fact that he's choosing to use it as a weapon in order to gain attention. We are extremely proud of our top-rated primetime hosts and all of our opinion programing,” Fox News said in a statement.

Here's Peters' full email to colleagues:

On March 1st, I informed Fox that I would not renew my contract. The purpose of this message to all of you is twofold:

First, I must thank each of you for the cooperation and support you've shown me over the years. Those working off-camera, the bookers and producers, don't often get the recognition you deserve, but I want you to know that I have always appreciated the challenges you face and the skill with which you master them.

Second, I feel compelled to explain why I have to leave. Four decades ago, I took an oath as a newly commissioned officer. I swore to "support and defend the Constitution," and that oath did not expire when I took off my uniform. Today, I feel that Fox News is assaulting our constitutional order and the rule of law, while fostering corrosive and unjustified paranoia among viewers. Over my decade with Fox, I long was proud of the association. Now I am ashamed.

In my view, Fox has degenerated from providing a legitimate and much-needed outlet for conservative voices to a mere propaganda machine for a destructive and ethically ruinous administration. When prime-time hosts--who have never served our country in any capacity--dismiss facts and empirical reality to launch profoundly dishonest assaults on the FBI, the Justice Department, the courts, the intelligence community (in which I served) and, not least, a model public servant and genuine war hero such as Robert Mueller--all the while scaremongering with lurid warnings of "deep-state" machinations-- I cannot be part of the same organization, even at a remove. To me, Fox News is now wittingly harming our system of government for profit.

As a Russia analyst for many years, it also has appalled me that hosts who made their reputations as super-patriots and who, justifiably, savaged President Obama for his duplicitous folly with Putin, now advance Putin's agenda by making light of Russian penetration of our elections and the Trump campaign. Despite increasingly pathetic denials, it turns out that the "nothing-burger" has been covered with Russian dressing all along. And by the way: As an intelligence professional, I can tell you that the Steele dossier rings true--that's how the Russians do things.. The result is that we have an American president who is terrified of his counterpart in Moscow.

I do not apply the above criticisms in full to Fox Business, where numerous hosts retain a respect for facts and maintain a measure of integrity (nor is every host at Fox News a propaganda mouthpiece--some have shown courage). I have enjoyed and valued my relationship with Fox Business, and I will miss a number of hosts and staff members. You're the grown-ups.

Also, I deeply respect the hard-news reporters at Fox, who continue to do their best as talented professionals in a poisoned environment. These are some of the best men and women in the business..

So, to all of you: Thanks, and, as our president's favorite world leader would say, "Das vidanya."